EP3285825B1 - Method and device for producing a medical solution - Google Patents

Description

The present invention relates to a method and an apparatus for producing a medical solution from at least one first and at least one second liquid component, wherein the first component and the second component are each conveyed with at least one conveying means in order to obtain at least one mixed solution.

From the prior art it is known to prepare dialysis solutions from two components, one of which is an acidic and the other a basic concentrate. Both components must be monitored in their concentration. This is done in known devices in that for each of the components, a conductivity sensor is provided in conjunction with a temperature measurement to take into account the temperature dependence of the conductivity.

The promotion of the components, i. Concentrates are carried out by means of concentrate pumps. If the determined conductivity values deviate from setpoints, a device alarm occurs.

As stated, the concentrations of the components, hereinafter also referred to as "partial components", are usually detected by individual conductivity sensors, so that a deviation from the respective setpoint independent of the sum concentration, ie from the concentration of the mixed solution containing the components can be detected.

The EP 2 494 998 A1 discloses an apparatus for manufacturing a medical solution having all the features of the preamble of claim 1.

A disadvantage of this known procedure is that a sensor cell is required for each component. Possibly. is used as a further protection system, another sensor cell for measuring the conductivity of the mixed solution, so that the overall result is a comparatively complex structure.

The present invention has for its object to simplify a method and an apparatus for producing a medical solution and in particular a dialysis solution, as used for example in hemodialysis, compared to the prior art.

This object is achieved by a method having the features of claim 1 and by an apparatus having the features of claim 7.

According to the invention it is provided inter alia that the conveying means are operated such that a modulation of the concentration of the first and the second component takes place and that measured at least one, preferably at exactly one measuring point, the conductivity of the mixed solution or a correlated with the conductivity parameters of the mixed solution is, wherein the modulation of the concentrations in a desired state such that a certain modulation (target modulation) or no modulation of the measured conductivity of the mixed solution or the conductivity-correlated parameter of the mixed solution occurs.

The present invention is therefore based on the idea to promote the components, such as the basic concentrate and the acidic concentrate so that the concentrations of the first component and the second component in the mixed solution are variable over time.

This modulation of the at least two components can be made such that the sum conductivity or the sum concentration correlated therewith, i. the conductivity or concentration of the mixed solution has no modulation, i. is constant in time or has a very specific desired modulation.

Used as part of the evaluation of the measured conductivity of the mixed solution or a parameter correlated therewith, e.g. the sum concentration of the mixed solution found that this is modulated or deviates in terms of their modulation from the specific target modulation, can be concluded that an error condition. This may be, for example, that one or both components are present in the mixed solution at too high or too low a concentration.

It is particularly advantageous if the modulation of the concentrations of the first and the second solution is carried out in such a way that no temporal variations in the conductivity or the concentration or a parameter correlated therewith occur in the mixed solution. If, in deviation from this nominal state, it is determined that the conductivity or a parameter correlated therewith is modulated, i. is not constant over time, can be concluded that an error condition.

Accordingly, an evaluation of the measured value of the mixed solution can be made as to whether there is a modulation of this value. If this is the case, an error condition can be concluded.

The same applies to the case in which a specific desired modulation of the sum concentration, conductivity etc. of the mixed solution is set, which represents the desired state, and then it is determined that the actual modulation deviates from the determined nominal modulation. Also in this case can be concluded that an error condition.

In an advantageous embodiment of the invention can be inferred from the type of fault condition on the component whose concentration deviates from the expected value. Thus, not only is there generally a fault condition, i. closed on a different state from the desired state, but it can be determined which of the several components is present in a concentration that deviates from the desired value.

It should be noted that the present invention is not limited to the use of exactly two solutions for producing a mixed solution, but that more than two solutions can be used.

The mixed solution may be the ready-to-use, administrable medical solution, in particular dialysis solution, or even a solution which becomes the finished medical solution, in particular dialysis solution, only after the addition of one or more further substances.

The method according to the invention can be carried out while the patient is not connected to the device for producing the solution. The invention also includes the case that the method is carried out in the sense of an online preparation of the solution while the patient is connected to the device.

The first component may be a basic concentrate and the second component may be an acidic concentrate. The basic concentrate has a pH of> 7 and a buffer, the acidic concentrate has a pH of <7 and a physiologically acceptable acid. One or both of the concentrates may contain electrolytes and optionally an osmotic agent.

The present invention allows the monitoring of the physiological properties of the partial components with a single conductivity cell or with a single sensor used to measure the concentration or a is suitable with this or with the conductivity correlated parameter. In addition, this cell or the sensor can be used to monitor the conductivity or the concentration of the mixed solution.

Thus, an advantageous embodiment of the invention is that no measurement of the conductivity or a correlated with the conductivity parameter of the first or the second component is made, but only the detection of a parameter, in particular the conductivity of the mixed solution.

Preferably, no serial delivery of the components is provided at the measuring point, since in a preferred embodiment of the invention the faulty component can be deduced from the measured property of the mixed solution.

• Amplitude der Modulation der gemessenen Leitfähigkeit der Mischlösung oder des mit der Leitfähigkeit korrelierten gemessenen Parameters der Mischlösung,
• mittlere gemessene Leitfähigkeit der Mischlösung oder Mittelwert des mit der Leitfähigkeit korrelierten gemessenen Parameters der Mischlösung,
• Phasenverschiebung der Modulation der gemessenen Leitfähigkeit der Mischlösung oder des mit der Leitfähigkeit korrelierten gemessenen Parameters der Mischlösung gegenüber der Anregung des Fördermittels.

It is preferably provided that one or more of the following parameters can be used to determine which component deviates in its concentration from the expected value for this component:

• The amplitude of the modulation of the measured conductivity of the mixed solution or of the conductivity-correlated measured parameter of the mixed solution,
• mean measured conductivity of the mixed solution or mean value of the conductivity-correlated measured parameter of the mixed solution,
• Phase shift of the modulation of the measured conductivity of the mixed solution or of the measured parameter of the mixed solution correlated with the conductivity compared to the excitation of the conveyor.

For the latter alternative, therefore, the excitation of the actuator or the conveying means for the component is detected, which / is preferably designed as a pump.

According to the invention, the modulation of the concentrations of the first and second components is sinusoidal.

The present invention further relates to a device for producing a medical solution, wherein the device has at least one first conveying means for conveying a first component and at least one second conveying means for conveying a second component and at least one main line, which is in communication with the conveying means in that the components are conveyed by the conveying means into the main line so that at least one mixed solution is formed in the main line, at least one, preferably exactly one, sensor for measuring the conductivity or a parameter of the mixed solution correlated with the conductivity being provided in the main line and that the conveying means are designed so that a modulation of the concentrations in a nominal state of the device takes place in such a way that a certain desired modulation or no modulation of the measured conductivity of the mixed solution or with the Leitf ability correlated measured parameter of the mixed solution occurs.

Preferably, the device has at least one evaluation unit, which is in communication with the sensor and which evaluates the signal detected by the sensor, wherein the evaluation unit is designed such that an error state is concluded when a modulation or one of the desired modulation deviating modulation of the measured conductivity of the mixed solution or of the conductivity-correlated measured parameter of the mixed solution is detected.

The evaluation unit may be designed in such a way that it is possible to determine from the type of error state which component deviates from the expected value in terms of its concentration.

As stated above, it is preferable to provide precisely one sensor for measuring the conductivity or a parameter of the mixed solution correlated with the conductivity.

Sensors for measuring the individual conductivity or a conductivity-correlated individual parameter of the first or the second component are preferably dispensed with.

The evaluation unit is preferably designed such that from the amplitude of the modulation of the measured conductivity or of the parameter correlated with the conductivity and / or from the average measured conductivity or from the mean value of the parameter correlated with the conductivity and / or from the phase shift of the modulation measured conductivity or the correlated with the conductivity parameter with respect to the excitation of the conveyor is determined, which component differs in concentration from the expected value for this component.

For comparison with the modulation of the conveyor means, a corresponding sensor or other detection means is provided which controls this modulation, i. detects the excitation of the pump or the like.

According to the invention, the modulation of the concentration of the first and the second component is sinusoidal.

The present invention further relates to a blood treatment device, in particular a dialysis machine, preferably for performing a hemodialysis treatment, wherein the blood treatment device comprises at least one device according to the invention for the preparation of the medical solution.

Figur 1:

die Summenleitfähigkeit der Komponenten A und B sowie den Beitrag der Einzelleitfähigkeiten der Komponenten A und B zur Summenleitfähigkeit,

Figur 2:

die Summenleitfähigkeit der Komponenten A und B sowie den Beitrag der Einzelleitfähigkeiten der Komponenten A und B zur Summenleitfähigkeit für vier verschiedene Zustände A bis C und

Figur 3:

eine schematische Ansicht eines Multikomponentensystems umfassend die Komponenten 1 bis N mit einer Leitfähigkeitsmesszelle zur Messung der Summenleitfähigkeit der Mischlösung.

Further details and advantages of the invention will be explained in more detail with reference to an embodiment shown in the drawing. Show it:

FIG. 1:

the sum conductivity of components A and B as well as the contribution of the individual conductivity of components A and B to the sum conductivity,

FIG. 2:

the sum conductivity of the components A and B and the contribution of Einzelleitfähigkeiten the components A and B to the total conductivity for four different states A to C and

FIG. 3:

a schematic view of a multi-component system comprising the components 1 to N with a conductivity measuring cell for measuring the total conductivity of the mixed solution.

Out FIG. 1 is the schematic time course of the Summenleitfähigkeit 100, ie the conductivity of the composite of the components A and B mixed solution over time visible. Furthermore, the time profiles of the conductivities of the components A and B (LF component A, LF component B) are shown such that the value for the conductivity of the component B (shown in dashed lines) is added to the value of the conductivity of the component A, see above that results in a temporally constant sum conductivity 100.

The embodiment relates to the measurement of the conductivity and is also conceivable for the measurement of any other parameter. The invention thus also encompasses the measurement of each other parameter of the mixed solution, which correlates with the conductivity or with the concentration, so that a conclusion can be drawn on the concentration of the components A and / or B or on their ingredients.

Out FIG. 1 It can be seen that the pump delivery of the components A and B is modulated in such a way that the sum conductivity 100 of the mixture has no modulation, ie is constant in time. The sum concentration, which is correlated with the sum conductivity, is therefore constant over time, whereas the concentrations of the components A and B in the mixed solution of both components vary over time.

The promotion of the partial components A and B takes place in the in FIG. 1 phase-shifted by π and phase-constant modulated so that the sum concentration is constant or the sum conductivity has no variations over time.

The amplitude of the concentration or conductivity variations, which in FIG. 1 is identical, is identical for the two components A and B.

$${\mathrm{LF}}_{\mathrm{B}}\left(\mathrm{t}\right)={\mathrm{C}}_{\mathrm{B}}\left(1+{\mathrm{f}}_{\mathrm{B}}\sin \left(\mathrm{\omega t}\right)\right)$$

Assuming that the partial components, ie the components A and B, which form the mixed solution or in this possibly present in a solvent, such as in particular water, in the mixed solution have the concentrations C _A and C _B and the Einzelleitfähigkeiten or conductivity contributions of the components A and B in the mixed solution LF _A (t) and LF _B (t), results in the relative amplitudes f _A and f _B and an ω modulation for the time course of the conductivities: $${\mathrm{LF}}_{\mathrm{A}}\left(\mathrm{t}\right)={\mathrm{<figure-callout\; id="1"\; label="C\; A"\; filenames="imgf0001.png"\; state="\{\{state\}\}">C\; </figure-callout>}}_{\mathrm{A}}\left(1+{\mathrm{f}}_{\mathrm{A}}\sin \left(\mathrm{.omega.t}\right)\right)$$

$${\mathrm{LF}}_{\mathrm{B}}\left(\mathrm{t}\right)={\mathrm{<figure-callout\; id="1"\; label="C\; B"\; filenames="imgf0001.png"\; state="\{\{state\}\}">C\; </figure-callout>}}_{\mathrm{B}}\left(1+{\mathrm{f}}_{\mathrm{B}}\sin \left(\mathrm{.omega.t}\right)\right)$$

The relative amplitude is the quotient of the absolute amplitude of the concentration fluctuation and the mean value of the concentration of component A or B in the mixed solution.

und aufgelöst nach f_A: $${\mathrm{f}}_{\mathrm{A}}=-{\mathrm{f}}_{\mathrm{B}}\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)$$

From the preferably desired freedom of modulation of the cumulative concentration or the cumulative conductivity over time results: $${\mathrm{C}}_{\mathrm{A}}{\mathrm{f}}_{\mathrm{A}}=-{\mathrm{C}}_{\mathrm{B}}{\mathrm{f}}_{\mathrm{B}}$$

and resolved to f _A : $${\mathrm{f}}_{\mathrm{A}}=-{\mathrm{f}}_{\mathrm{B}}\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)$$

mit f_AB = C_B/C_A.If one sets the relative amplitude of the modulation of component B, for example to the value 0.5, the result is: $${\mathrm{f}}_{\mathrm{A}}=-0.5\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)=-0.5{\mathrm{f}}_{\mathrm{FROM}}$$

with f _AB = C _B / C _A.

Thus, the relative amplitude f _{A of} the component A results directly from the desired ratio of the concentrations of the components B and A in the mixed solution and the relative amplitude f _{B of} the component B.

The measured sum conductivity, ie the conductivity of the mixed solution composed of the individual components A and B, will have the desired physiological expected value in the desired state or correlate with the expected sum concentration, ie the sum of the concentration of the individual components A and B. For the above example with f _B = 0.5 then the equations (1), (2) and (5) result: $${\mathrm{LF}}_{\mathrm{A}}\left(\mathrm{t}\right)+{\mathrm{LF}}_{\mathrm{B}}\left(\mathrm{t}\right)={\mathrm{C}}_{\mathrm{A}}\left(1-0.5\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)\sin \left(\mathrm{.omega.t}\right)\right)+{\mathrm{<figure-callout\; id="1"\; label="C\; B"\; filenames="imgf0001.png"\; state="\{\{state\}\}">C\; </figure-callout>}}_{\mathrm{B}}\left(1+0.5\sin \left(\mathrm{.omega.t}\right)\right)={\mathrm{C}}_{\mathrm{A}}+{\mathrm{C}}_{\mathrm{B}}$$

The expected values C _A and C _B in the mixed solution are constant in time, so that there is also a temporal constancy with regard to the sum conductivity LF _A (t) + LF _B (t).

If the contribution of a component A or B deviates from the respective expected value, the sum conductivity is modulated. Depending on which component deviates in terms of concentration from the expected value, a certain modulation of the sum conductivity is generated, ie the measurement of the Total conductivity produces a characteristic fingerprint. Thus, it can be determined based on the measurement of the sum conductivity, which component deviates from the expected value.

If it is assumed that the component B in terms of their concentration in the mixed solution does not match the expected value C _B, but only the value C _B having 'representing a certain fraction 1 / α of the expected value C _B yields: $${\mathrm{C}}_{\mathrm{B}}\text{'}=1/\mathrm{\alpha }{\mathrm{C}}_{\mathrm{B}}$$

$$={\mathrm{C}}_{\mathrm{A}}+1/\mathrm{\alpha }{\mathrm{C}}_{\mathrm{B}}+\left(1/\mathrm{\alpha }-1\right){\mathrm{C}}_{\mathrm{B}}/2\sin \left(\mathrm{\omega t}\right)$$

The sum conductivity thus does not have the value resulting from equation (6) in this case, but, taking into account equation (5) and (7), yields: $${\mathrm{LF}}_{\mathrm{A}}\left(\mathrm{t}\right)+{\mathrm{LF}}_{\mathrm{B}}\left(\mathrm{t}\right)={\mathrm{C}}_{\mathrm{A}}\left(1-0.5\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)\sin \left(\mathrm{.omega.t}\right)\right)+{\mathrm{C}}_{\mathrm{B}}\text{'}\left(1+0.5\sin \left(\mathrm{.omega.t}\right)\right)$$

$$={\mathrm{C}}_{\mathrm{A}}+1/\mathrm{\alpha }{\mathrm{C}}_{\mathrm{B}}+\left(1/\mathrm{\alpha }-1\right){\mathrm{C}}_{\mathrm{B}}/2\sin \left(\mathrm{.omega.t}\right)$$

If the component contribution of component B thus deviates from the expected value by a factor of 1 / α, then the conductivity of the sum concentration, ie the mixed solution of the two components A and B modulates the amplitude (1 / α-1) C _B / in this exemplary embodiment. second

The mean sum conductivity corresponds or correlates in this case with C _A + 1 / α C _B.

If it is assumed that the component A with respect to their concentration does not correspond to the expected value of C _A, but only the value of C _A having 'that a certain fraction 1 / β of the expected value C represents _A, yields: $${\mathrm{C}}_{\mathrm{A}}\text{'}=1/\mathrm{\beta }{\mathrm{C}}_{\mathrm{A}}$$

$$=1/\mathrm{\beta }{\mathrm{C}}_{\mathrm{A}}+{\mathrm{C}}_{\mathrm{B}}+\left(1-1/\mathrm{\beta }\right){\mathrm{C}}_{\mathrm{B}}/2\sin \left(\mathrm{\omega t}\right)$$

The sum conductivity thus does not have the value resulting from equation (6) in this case, but, taking into account equations (5) and (10), yields: $${\mathrm{LF}}_{\mathrm{A}}\left(\mathrm{t}\right)+{\mathrm{LF}}_{\mathrm{B}}\left(\mathrm{t}\right)=1/\mathrm{\beta }{\mathrm{C}}_{\mathrm{A}}\left(1-0.5\left({\mathrm{C}}_{\mathrm{B}}/{\mathrm{C}}_{\mathrm{A}}\right)\sin \left(\mathrm{.omega.t}\right)\right)+{\mathrm{<figure-callout\; id="1"\; label="C\; B"\; filenames="imgf0001.png"\; state="\{\{state\}\}">C\; </figure-callout>}}_{\mathrm{B}}\left(1+0.5\sin \left(\mathrm{.omega.t}\right)\right)$$

$$=1/\mathrm{\beta }{\mathrm{C}}_{\mathrm{A}}+{\mathrm{C}}_{\mathrm{B}}+\left(1-1/\mathrm{\beta }\right){\mathrm{C}}_{\mathrm{B}}/2\sin \left(\mathrm{.omega.t}\right)$$

If the component contribution of component A deviates by the factor 1 / β from the expected value, then the conductivity of the sum concentration, ie the mixed solution of the two components A and B modulates in this embodiment with the amplitude (1 - 1 / β) C _B / second

The mean sum conductivity corresponds or correlates with 1 / β C _A + C _B in this case.

The average conductivity, its amplitude, and the phase versus actuator excitation of the component promotion identify the component whose concentration deviates from the expected value.

If the components make a different contribution to the sum concentration, a compensating deviation among the components can also be identified.

FIG. 2 shows in the state A the case that the expected values of the contributions of the components A and B is reached. In this case, the sum conductivity 100 or the sum concentration of the mixed solution shows no modulation, ie is constant over time. Reference numerals 10 and 20 indicate the time course of the contributions of the conductivity or the concentration of the partial components A. (Reference 10) and B (Reference 20) for conductivity 100 or concentration of the mixed solution.

In state B, the expected value 20 of component B is reached, but the actual value of the concentration 10 of component A is below the expected value. The sum conductivity 100 or the sum concentration is below the expected value and is phase-shifted modulated with the deviating component A.

In the state C, the expected value 10 of the component A is reached, but the actual value of the concentration 20 of the component B is below the expected value. The sum conductivity 100 or the sum concentration is below the expected value and is phase-shifted modulated with the deviating component B.

In state D, both expected values of components A and B are not reached. The deviation, however, is compensatory, i. the sum contribution corresponds to the expected value, i. the mean value of the sum conductivity 100 or the sum concentration corresponds to the expected value.

However, in this case too, the sum conductivity 100 or the sum concentration is modulated, i. not constant in time.

A deviation of the concentration contributions of the components A and B can thus be made from the analysis of the modulated sum concentration or sum conductivity.

From this analysis results the phase shift of the modulation of the sum concentration or the sum conductivity compared to the phases of the concentrate feed pumps.

The mean expected value of the sum concentration or the sum conductivity indicates an over or under promotion of the deviating component, i. the measured average of the sum conductivity or the sum concentration indicates an over- or under-promotion of the deviating component.

Thus, for example, from the state B in FIG. 2 not only that the component A is present with a deviating from the expected value concentration, but also that there is a sub-promotion with respect to this component.

FIG. 3 shows a multi-component system with modulated promotion of the concentrations of components 1 to N. All components are conveyed in a main line H, in which the only conductivity cell (LF cell) is located. The respective modulations are characteristic of each component in terms of frequency and phase. This characteristic allows an identification of the contribution deviating from the expected value of a component.

By determining the phase shift of the amplitude of the sum conductivity or the sum concentration to the phase of the concentrate feed pump, even a compensatory deviation of the components can be determined, which does not lead to a change in the average sum conductivity or sum concentration.

According to the invention, for monitoring the contributions of the individual, i. the partial components only a single or a single conductivity or concentration sensor or the like required. The components are added via modulated conveying concentrate pumps to the main line, in which the sensor is located.

Instead of a conductivity sensor or a concentration sensor, any other sensor can be used, which inferences on the concentrations or Leifähigkeiten the components or on the cumulative concentration or on the total conductivity allowed.

Claims (13)

1. A method for preparing a medical solution from at least one first component and at least one second component, wherein
   the first component and the second component are present as liquids and are respectively conveyed by a conveying means to obtain a mixed solution,
   the conveying means are operated such that a modulation of the concentrations of the first and second components takes place,
   at a measurement point the conductivity or a parameter of the mixed solution correlating with the conductivity is measured, and
   the modulation of the concentrations of the components takes place in a desired state such that a specific desired modulation or no modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity occurs,
   characterized in that
   the modulation of the first and the second component takes place continuously sinusoidal.
2. The method in accordance with claim 1, characterized in that an evaluation of the measured conductivity or of the measured value of the parameter of the mixed solution correlated with the conductivity is carried out and a conclusion is drawn on an error state upon occurrence of a modulation or a deviation from the desired modulation.
3. The method in accordance with one of the preceding claims, characterized in that the medical solution is a dialysis solution; and/or in that the first component is a base concentrate and the second component is an acid concentrate.
4. The method in accordance with one of the preceding claims, characterized in that no measurement of the conductivity or of a parameter correlated with the conductivity of the first or second component is carried out.
5. The method in accordance with one of the preceding claims, characterized in that no serial conveying of the components past the measurement point takes place.
6. The method in accordance with one of the preceding claims, characterized in that a determination is made from the amplitude of the modulation of the measured conductivity of the mixed solution or of the measured parameter of the mixed solution correlated with the conductivity of the mixed solution and/or from the mean measured conductivity of the mixed solution or from the mean value of the measured parameter of the mixed solution correlated with the conductivity and/or from the phase shift of the modulation of the measured conductivity of the mixed solution or of the measured parameter of the mixed solution correlated with the conductivity in relation to the stimulation of the conveying means, as to which component deviates in its concentration from the expected value for this component.
7. A device for producing a medical solution, comprising:

   a first conveying means for conveying a first component,

   a second conveying means for conveying a second component, as well as

   a main line which is in communication with the conveying means such that the components are conveyed into the main line by the conveying means so that a mixed solution is created in the main line, wherein

   a sensor is provided in the main line for measuring the conductivity or of a parameter of the mixed solution correlated with the conductivity, and

   the conveying means are configured such that a modulation of the concentrations of the components takes place in a desired state such that no modulation or a specific desired modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity occurs,

   characterized in that

   the conveying means are configured such that the modulation of the concentrations of the first and the second components takes place continuously sinusoidal.
8. The device in accordance with claim 7, characterized in that the device comprises an evaluation unit to which the signal detected by the sensor is supplied, wherein the evaluation unit is configured such that an error state is concluded when a modulation or a modulation of the measured conductivity or of the parameter of the mixed solution correlated with the conductivity deviating from the desired modulation is detected.
9. The device in accordance with claim 8, characterized in that the evaluation unit is configured such that it can be determined from the kind of error state which component deviates with respect to its concentration from the expected value for this component.
10. The device in accordance with one of the claims 7 to 9, characterized in that exactly one sensor is provided for measuring the conductivity or a parameter of the mixed solution correlated with the conductivity.
11. The device in accordance with one of the claims 7 to 10, characterized in that no sensor is provided for measuring the conductivity or a parameter of the first or the second components correlated with the conductivity.
12. The device in accordance with one of the claims 7 to 11, characterized in that an evaluation unit is configured such thata determination is made from the amplitude of the modulation of the measured conductivity of the mixed solution or of the measured parameter of the mixed solution correlated with the conductivity and/or from the mean measured conductivity of the mixed solution or from the mean value of the measured parameter of the mixed solution correlated with the conductivity and/or from the phase shift of the modulation of the measured conductivity of the mixed solution or of the measured parameter of the mixed solution correlated with conductivity in relation to the stimulation of the conveying means, as to which component deviates in its concentration from the expected value for this component.
13. A blood treatment device, in particular a dialysis machine, having a device in accordance with one of the claims 7 to 12.

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